Biology subjects

Sheffer, M. M.

Publications and source records attributed to Sheffer, M. M..

6 recordsLinked to original sources

bioRxiv2026

Genomic insights into Candidatus Argioplasma dusa, a bacterial symbiont of the wasp spider Argiope bruennichi

Bacterial symbionts were shown to have significant beneficial impacts on the fitness of their host in insects, but little is known on the symbionts of spiders and their interactions with their hosts. Here, we assembled and investigated the circular 575 kb genome of Candidatus Argioplasma dusa, a novel bacterial symbiont of the wasp spider Argiope bruennichi. Phylogenomic analysis placed this species within the phylum Tenericutes, in a poorly characterized clade that may represent a new order-level lineage or affiliate with the Mycoplasmatales order. With 559 predicted genes, the genome is relatively small compared to other Tenericutes genomes (on average 969 genes) and has a low GC content of ~24%. While the genome encodes genes for proteins involved in glycolysis and fermentative acetate production, it revealed minimal biosynthetic capabilities with pathways for nucleotide, amino acid and vitamin biosynthesis being absent in Ca. Argioplasma dusa. This suggests an intracellular endosymbiotic lifestyle within the spider host. The symbiont was detected in A. bruennichi populations across the distribution range of the spider but appears to be absent in certain populations.

microbiology↗

bioRxiv2021

Rapid ecological and evolutionary divergence during a poleward range expansion

In response to climate change, a northward range expansion has been observed in many species. The wasp spider, Argiope bruennichi, has expanded from its historic range in the Mediterranean ("core"), now reaching as far as the Baltic States and Scandinavia ("edge"), even faster than the pace of climate change. We explored life history traits, adult phenotypes, offspring cold tolerance, and genomic patterns across the European range of A. bruennichi, and found origin-, environment- and life stage-specific responses to the cold northern climate. Wasp spiders have shifted their phenology at the edge, with females maturing earlier and at a smaller size, but maintaining similar pigmentation, clutch sizes, and hatching success compared to the core region. Using a reciprocal common garden experiment on overwintering offspring from the core and edge, we found evidence for genetic adaptation and considerable phenotypic plasticity. Overwintering survival was lower under the cold winter treatment for spiderlings from both origins. However, the edge-origin spiderlings that survived the winter had lower lethal temperatures and enhanced supercooling ability with reduced phenotypic plasticity in supercooling points compared to core spiderlings, while the chill coma recovery time was similar. Metabolomic analysis revealed accumulations of amino acids and myo-inositol in the cold winter treatment, particularly in spiderlings from the edge population, suggesting a role of these metabolites in improving cold tolerance. Genotype-environment tests showed strong genetic association across the genome to seasonality and minimum winter temperature. The population genomic analysis across the European range splits A. bruennichi into two distinct genetic clusters through the center of Germany, which roughly aligns with turnover from an oceanic to continental climate zone, complementing the genotype-environment test results. Overall, our study highlights the importance of integrating data on phenological shifts, changes in life-history, and life stage-specific phenotypic plasticity and genetic adaptation to understand the impacts of range expansions and shifts. The nuanced processes of acclimation and adaptation we uncovered advocate for holistic investigations of evolutionary fitness and fitness-related traits in the context of organismal responses to novel and changing environments.

ecology↗

bioRxiv2021

Identification of sex chromosomes using genomic and cytogenetic methods in a range-expanding spider, Argiope bruennichi (Araneae: Araneidae)

Differences between sexes in growth, ecology and behavior strongly shape species biology. In some animal groups, such as spiders, it is difficult or impossible to identify the sex of juveniles based on external morphology. This information would be useful for field surveys, behavioral experiments, and ecological studies on e.g. sex ratios and dispersal. In species with sex chromosomes, sex can be determined based on the specific sex chromosome complement. Additionally, information on the sequence of sex chromosomes provides the basis for studying sex chromosome evolution. We combined cytogenetic and genomic data to identify the sex chromosomes in the sexually dimorphic spider Argiope bruennichi, and designed RT-qPCR sex markers. We found that genome size and GC content of this spider falls into the range reported for the majority of araneids. The male karyotype is formed by 24 acrocentric chromosomes with an X1X20 sex chromosome system, with little similarity between X chromosomes, suggesting origin of these chromosomes by X chromosome fission or early duplication of an X chromosome and subsequent independent differentiation of the copies. Our data suggest similarly sized X chromosomes in A. bruennichi. They are smaller chromosomes of the complement. Our findings open the door to new directions in spider evolutionary and ecological research.

genetics↗

bioRxiv2020

Chromosome-level genome assembly of a benthic associated Syngnathiformes species: the common dragonet, Callionymus lyra

BackgroundThe common dragonet, Callionymus lyra, is one of three Callionymus species inhabiting the North Sea. All three species show strong sexual dimorphism. The males show strong morphological differentiation, e.g., species-specific colouration and size relations, while the females of different species have few distinguishing characters. Callionymus belongs to the benthic associated clade of the order Syngnathiformes. The benthic associated clade so far is not represented by genome data and serves as an important outgroup to understand the morphological transformation in long-snouted syngnatiforms such as seahorses and pipefishes. FindingsHere, we present the chromosome-level genome assembly of C. lyra. We applied Oxford Nanopore Technologies long-read sequencing, short-read DNBseq, and proximity-ligation-based scaffolding to generate a high-quality genome assembly. The resulting assembly has a contig N50 of 2.2 Mbp, a scaffold N50 of 26.7 Mbp. The total assembly length is 568.7 Mbp, of which over 538 Mbp were scaffolded into 19 chromosome-length scaffolds. The identification of 94.5% of complete BUSCO genes indicates high assembly completeness. Additionally, we sequenced and assembled a multi-tissue transcriptome with a total length of 255.5 Mbp that was used to aid the annotation of the genome assembly. The annotation resulted in 19,849 annotated transcripts and identified a repeat content of 27.66%. ConclusionsThe chromosome-level assembly of C. lyra provides a high-quality reference genome for future population genomic, phylogenomic, and phylogeographic analyses.

genomics↗

bioRxiv2020

Chromosome-level reference genome of the European wasp spider Argiope bruennichi: a resource for studies on range expansion and evolutionary adaptation

BackgroundArgiope bruennichi, the European wasp spider, has been studied intensively as to sexual selection, chemical communication, and the dynamics of rapid range expansion at a behavioral and genetic level. However, the lack of a reference genome has limited insights into the genetic basis for these phenomena. Therefore, we assembled a high-quality chromosome-level reference genome of the European wasp spider as a tool for more in-depth future studies. FindingsWe generated, de novo, a 1.67Gb genome assembly of A. bruennichi using 21.5X PacBio sequencing, polished with 30X Illumina paired-end sequencing data, and proximity ligation (Hi-C) based scaffolding. This resulted in an N50 scaffold size of 124Mb and an N50 contig size of 288kb. We found 98.4% of the genome to be contained in 13 scaffolds, fitting the expected number of chromosomes (n = 13). Analyses showed the presence of 91.1% of complete arthropod BUSCOs, indicating a high quality of the assembly. ConclusionsWe present the first chromosome-level genome assembly in the class Arachnida. With this genomic resource, we open the door for more precise and informative studies on evolution and adaptation in A. bruennichi, as well as on several interesting topics in Arachnids, such as the genomic architecture of traits, whole genome duplication and the genomic mechanisms behind silk and venom evolution.

genomics↗

bioRxiv2019

Tissue- and population-level microbiome analysis of the wasp spider Argiope bruennichi identifies a novel dominant bacterial symbiont

Many ecological and evolutionary processes in animals depend upon microbial symbioses. In spiders, the role of the microbiome in these processes remains mostly unknown. We compared the microbiome between populations, individuals, and tissue types of a range-expanding spider, using 16S rRNA gene sequencing. Our study is one of the first to go beyond targeting known endosymbionts in spiders, and characterizes the total microbiome across different body compartments (leg, prosoma, hemolymph, book lungs, ovaries, silk glands, midgut, and fecal pellets). Overall, the microbiome differs significantly between populations and individuals, but not between tissue types. The microbiome of the wasp spider Argiope bruennichi features a novel dominant bacterial symbiont, which is abundant in every tissue type in spiders from geographically distinct populations, and present in offspring. The novel symbiont is affiliated with the Tenericutes, but has low sequence identity (<85%) to all previously named taxa, suggesting that the novel symbiont represents a new bacterial clade. Its presence in offspring implies that it is vertically transmitted. Our results shed light on the processes which shape microbiome differentiation in this species, and raise several questions about the implications of the novel dominant bacterial symbiont on the biology and evolution of its host.

microbiology↗